BLOOD-VESSELS OF STOMACH IN THE HORSE. 41 



mals in general, owing to the loose connection between the 

 mucous coat and the immediately subjacent textures, as well 

 as to the smaller elasticity of the internal lining. The mucous 

 coat of the stomach, as seen in the right half of the cavity, is 

 a smooth, soft, rather thick, and pulpy membrane, which has 

 generally a rather pale pink hue, though, when well washed, 

 it is of a greyish-white or pale straw colour. During digestion 

 its vessels become distended, and, when examined in that state, 

 it is always much darker than usual. The mucous coat of the 

 stomach is often described as villous ; but it does riot appear 

 that there are any true villi in the stomachs of animals, these 

 minute structures being found only in the small intestines, as 

 in the duodenum and jejunum. What have been mistaken for 

 villi in the stomach are the elevated margins of minute alveoli 

 that is to say, little depressions or pits visible with the aid 

 of a lens, especially near the pylorus. The microscope exhibits, 

 in the mucous membrane of the stomach, a number of minute 

 tubules set side by side perpendicularly to the surface of the 

 membrane : some of these have been supposed to possess a 

 glandular structure, and to be specially concerned in the se- 

 cretion of the gastric juice, whence they have been termed 

 peptic glands. 



The stomach is very copiously supplied with blood by its 

 proper arteries. An important blood-vessel, the aorta or great 

 systemic artery, arises from the left ventricle of the heart, and 

 divides opposite the fourth dorsal vertebra into an anterior 

 and posterior aorta the latter being directed backwards, so 

 that after giving branches to the parts within the chest, it 

 passes between what are called the crura of the diaphragm, and 

 becomes the abdominal aorta, the inferior aspect of which, 

 immediately after it has penetrated the diaphragm, gives origin 

 to a very short stump, which is called the cosliac artery. This 

 short stump or root immediately breaks into three arteries 



